• Composites Research
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• v.33 no.4
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• pp.198-204
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• 2020

In this study, we employ the full atomistic molecular dynamics simulation and finite element homogenization method to predict the thermo-mechanical properties of nanocomposites including carbon nanotube bundle. As the number of carbon nanotubes within the single bundle increases, the effective in-plane Young's modulus and in-plane shear modulus decrease, and in-plane thermal expansion coefficient increases, despite the same volume fraction of carbon nanotubes. To investigate the thickness of interphase zone, we employ the radial density distribution. It is investigated that the interphase thickness is almost independent on the number of carbon nanotubes within the single bundle. It is assumed that the matrix and interphase are isotropic materials. According to the predicted thermo-mechanical properties of interphase zone, the Young's modulus and shear modulus of interphase zone clearly decrease, and the thermal expansion coefficient increases. Based on the thermo-mechanical interphase behavior, we developed the multiscale homogenization model to predict the thermo-mechanical properties of PLA nanocomposites that include the carbon nanotube bundle.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1118-1124
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• 2023

Experimental study on the fluidelastic instability (FEI) of a curved tube bundle in single phase downward cross flow is investigated for the design qualification and analysis input preparation of helical coiled steam generator tubing. A 6×9 normal square curved tube array with equal and different vertical/horizontal pitch-to-diameter ratio was under-tested up to 6 m/s in term of gap flow velocity to measure the critical velocity for FEI. The critical velocity for FEI was measured at the turning point from the vibration amplitude plot along the gap flow velocity. Our test results were compared with straight tube results and published data in the design guideline. The applicability of the current design guidelines to a curved tube bundle is also assessed. We found that introducing frequency difference in a curved tube array increases the critical velocity for fluidelastic instability.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2089-2097
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• 2014

Negative corona onset characteristics of the stranded conductors based on the ultra-high voltage (UHV) corona cage were studied in the paper. Based on the corona self-sustaining criterion in extreme uneven electric fields and the secondary emission process of the photoelectrons, the corona onset calculation model in the UHV corona cage is established and the corona current tests of the single LGJ900-75, 6 bundle LGJ900-75, 8 bundle LGJ400-35 conductors in dry and rain conditions were done in the UHV corona cage, and the rain rates are 2.4 mm/h, 20 mm/h and 30 mm/h. Corona onset electric field strength is gained by E-I tangent method, and the onset electric field strength in dry condition proves that the calculation model can be used to calculate the corona onset characteristics of the bundle conductors in the UHV corona cage. A further analysis proves that: the negative corona onset voltage of the conductor increases with the bundle number and the diameter of the sub conductor, but decreases with the bundle space in the corona cage. The onset electric field strength is influenced little by bundle space and bundle number, but decreases with the increase of the diameter of the sub-conductor. The surface irregularity coefficient decreases with the rain rate.

• Journal of Korean Biological Nursing Science
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• v.18 no.4
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• pp.257-263
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• 2016

Background: This study purposed to examine how the incidence of the central line-associated bloodstream infection (CLABSI) in a operating room (OR) is affected by bundle application on central line insertion (CLI) practice. Methods: The study design was a pretest-posttest experimental trial. The subjects were 83 patients before the bundle application on CLI and 70 patients after. Results: The compliance(%) of bundle on CLI of among those who observed all of the five items increased from 7.2% before the intervention to 72.9% after. By items, compliance with the maximal barrier precaution was 100% for the use of a mask and cap before and after the intervention, but increased from 73.5% before the intervention to 88.6% after for the hand hygiene, from 73.5% to 88.6% for the use of a sterile gown, and from 9.6% to 75.7% for the use of a sterile large drape covering the whole body. CLABSI did not happen on CLI either before or after the application of the bundle intervention. Conclusion: Bundle application increased compliance with the use of a sterile gown and the use of a sterile large drape. However, its effect in the prevention of CLABSI was not clear probably due to the short period of intervention in a single hospital.

• Journal of the Korean Arthroscopy Society
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• v.13 no.2
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• pp.111-114
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• 2009

Double-bundle anterior cruciate ligament reconstruction (DBACLR) has been developed to produce better clinical outcomes in traditional single-bundle reconstruction, which showed considerable rate of dissatisfaction in restoration of stability and function of the anterior cruciate ligament deficient knee. There is plenty of evidence that DBACLR has theoretical advantages in anatomical, biomechanical, biological, kinematical, and possibly clinical standpoint compared with traditional one but still a lack of available clinical outcome studies with sufficient follow-up to demonstrate the substantial advantages of DBACLR. The purpose of this article is to review the clinical outcomes of double-bundle technique and to address controversy exists over the usefulness of this technique.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.3
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• pp.81-87
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• 2009

The effect of oil on convective boiling of R-123 in an enhanced tube bundle is experimentally investigated at $26.7^{\circ}C$ saturation temperature. The enhanced tube had pores (0.23 mm diameter) and connecting gaps (0.07 mm width), which had been optimized using pure R-123. The effects of oil concentration (0 to 5%), heat flux (10 to $40\;kW/m^2$), mass velocity (8 to $26\;kg/m2^s$) and vapor quality are investigated. The oil significantly reduces the bundle boiling heat transfer coefficient. With 1% oil, the reduction is approximately 35%. Further addition of oil further reduces the heat transfer coefficient. The data are also compared with the pool boiling counterpart. The reduction in the heat transfer coefficient is smaller in a bundle (convective boiling) than in a pool (single-tube pool boiling), with larger difference at a smaller heat flux. Similar to pure R-123 case, the effects of mass velocity and vapor quality are negligible for the convective boiling of R-123/oil mixture.

• Journal of the Korean Arthroscopy Society
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• v.12 no.3
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• pp.167-171
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• 2008

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4296-4309
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• 2022

Mesh and turbulence model sensitivity analyses have been performed on computational fluid dynamics simulations executed with Hydra and ANSYS Fluent for a single CANadian Deuterium Uranium (CANDU) 37M nuclear fuel bundle placed within a standard pressure tube. The goal of this work was to perform a methodical analysis to objectively determine an appropriate mesh and to gauge the sensitivity of different turbulence models for CANDU subchannel flow under isothermal conditions. The boundary conditions and material properties are representative of normal operating conditions in a high-powered channel of the Darlington Nuclear Generating Station. Four meshes were generated with ANSYS Workbench Meshing, ranging from 22 to 84 million cells, and analyzed here to determine an appropriate level of mesh resolution and quality. Five turbulence models were compared in the turbulence model sensitivity analysis: standard k - ε, RNG k - ε, realizable k - ε, SST k - ω, and the Reynolds Stress Model. The intent of this work was to gain confidence in mesh generation and turbulence model selection of a single bundle to inform the decision making of subsequent investigations of an entire fuel channel containing a string of twelve bundles.

• 대한관절경학회:학술대회논문집
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• 2008.04a
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• pp.14-14
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• 2008

• 대한관절경학회:학술대회논문집
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• 2008.04a
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• pp.12-13
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• 2008